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Novel Skin Test Could Replace Animal Testing for Drugs and Cosmetics

A team at Newcastle University in the UK has developed a new testing technique that uses human tissue to measure drug reactions.

A new medical technology uses human tissue samples to predict how skin will react to drugs, makeup, and chemicals.

The testing technique, called Skimune, involves taking blood and skin tissue samples from human donors and culturing, or growing, them in the lab.

The substance being tested is mixed with the donor’s immune cells, activating them to respond in the way they would inside the body. The activated cells are then exposed to the same donor’s skin cells.

By observing how the skin sample reacts to its own immune cells, researchers can get a good idea of whether the substance would cause an allergic reaction in the person’s skin.

“We know the toxicology of compounds,” lead researcher Professor Anne Dickinson of Newcastle University said in an interview with Healthline, “but we want to look at the immune response, and you can’t know the immune response without looking at the immune cells.”

The substance never comes in direct contact with the skin sample, as occurs in current toxicology tests used to determine whether a substance is poisonous, corrosive, or otherwise hazardous to humans.

“There are a lot of toxicology methods out there, but they don’t at the moment involve the use of immune cells to look at damage in the skin. We’re looking for an adverse immune response, rather than a toxic response. Cell lines can’t do that. 3D models can’t look at that effect,” Dickinson said. “We’re not looking to replace toxicology, but to offer a complement. It’s a test which would be in addition to the tests that are currently run, to give more confidence and more information.”

The Present and Future of Drug Testing

Dickinson is the director and founder of Alcyomics, a company she and her colleagues formed to patent Skimune and bring it to market as a viable testing technique.

The development has come just in time, as the European Union banned the sale of cosmetics tested on animals in March following a January restriction on the use of animal testing for scientific purposes. Although no such ban exists in the U.S., animal testing is subject to strict regulation, especially during drug discovery. Skimune could offer a more accurate, safer, and cheaper alternative for pharmaceutical companies.

During testing with more than 40 compounds, Skimune's findings were 98 percent similar to findings in mice. Among the remaining two percent, the test detected adverse reactions where mouse tests did not, and correctly predicted there would be no human allergic reaction when the mice did react.

“There’s a species difference,” Dickinson explained. "We're very nearly 100 percent of being able to reveal whether a compound will be a problem or not."

Testing any experimental substance on human subjects can be dangerous, so researchers first look to measure its safety and effectiveness in other ways. They currently have a few options, each with its own limitations.

They can test the chemical on a petri dish of basic human cells, but this often doesn’t indicate how the substance will behave in a whole, living person.

Alternatively, they can test the substance on animals, and, ethical issues aside, animals like rats often aren’t a good model for how humans will respond to a given treatment. Every species is different. For example, chocolate is a tasty treat for humans, but a deadly poison for dogs and cats.

This difference was illustrated vividly in 2006, in a drug study at Northwick Park Hospital in London. There, six healthy young men experienced organ failure during a clinical trial after taking a drug that had been found to be safe in macaque monkeys. One even lost his fingers and toes.

Alcyomics tested TGN1412, the drug that caused such trouble at Northwick Park. Their results were clear: Skimune could have detected the adverse reactions before the drug made it to human trials.

The test is sensitive enough to allow researchers to gather information not just about the safety of drugs, but also what doses to use, how skin will react to prolonged exposure to a drug, how different individuals might react to the same drug, and other knowledge that is dangerous and costly to gather in human trials.

Alcyomics advertises turnaround times of as little as two weeks. Since the test is quick to run, it allows drug and cosmetics companies to test a large number of similar chemicals at the same time. For example, hydrolyzed wheat protein—a common ingredient in many hair products—is actually a generic name for dozens of related chemicals. A new formula might replenish hair, but Skimune can help determine whether it will cause an allergic reaction when it comes in contact with skin.

Although Alcyomics is still in the process of patenting their technology, they are already using Skimune to test drugs in preclinical trials. They will need Food and Drug Administration (FDA) approval to use Skimune as a diagnostic tool on human subjects, a process that takes years. But if they receive it, they might have a new alternative not just for cosmetic and drug testing, but also for the allergy stick test, which involves pricking a patient's back with dozens of tiny needles that contain common allergens like pollen and cat dander.